Take some plumbing advice cautiously

[Rabbit]

There’s a reason plumbers have to be certified/licensed. Doing a plumbing job wrong can result in property damage, health related dangers, not to mention inconvenience or wasted money. I have over fourth years in the drinking water industry with a leading company that makes fittings for water and gas lines, including the sorts used in RVs. I cringe when I read posts that give advice for connecting PEX pipe, replacing a vacuum breaker, not using a water pressure regulator, or modifying the propane piping. All of these involve observing product specifications, government regulations or good practices guidelines. Two of my pet peeves involve PEX, and black tank flush systems. PEX pipe is the extruded plastic pipe used in buildings and RVs. This pipe (rigid or flexible) has a hard smooth Outside and inside surface. Braided tubing is not interchangeable in all applications. Braided tubing is soft and has an outside surface that is not uniform (smooth). Fittings that rely on an o-ring to seal, such as SharkBite brand and similar, are not certified for use on braided tubing. Barbed fittings with pipe clamps (worm gear, even PEX clamps) are about the only reliable connection. O-ring fitting MIGHT be made to seal, but the seal will not be reliable for the long term, especially with vibration.

Black flush systems involve dangerous waste. The vacuum breaker in the water line is REQUIRED and must be installed high up above all drains in the RV. Don’t ever defeat it by replacing with a piece of tubing, or install it lower than any drain or toilet bowl.

Pressure regulators should always be used, especially in hilly or mountainous areas.

If you must have the details, do your research. Or better yet, call a licensed plumber or trained tech person.

 

[Always Learning]

With your experience what do you think about the way Grand Design mixes the soft hose and PEX in the construction of their trailers. If you have not had any problems with the plumbing in your trailer then that is great. What ever you do don’t touch the connections behind the Nautilus panel. I replaced my water pump the other day and in the process caused one of the connections behind the Nautilus to leak. By the time I got that connection fixed a three way tee was leaking. By the time I got the leaks fixed I had spent all afternoon. The braided soft hose GD uses is slightly larger OD than PEX and needs to be heated to get PEX clamps on and the ID is much larger than the PEX connectors that GD uses which causes the leaks.

What are your recommendations for fixing the soft hose leaks that result from GD using PEX connectors that are much smaller then the soft hose ID?

 

[TravelHabit]

... PEX pipe is the extruded plastic pipe used in buildings and RVs.

Mine is all braided tubing as far as I can tell. I'm thinking of replacing it so everything is PEX. GD says braided tubing is the "industry standard" but that does not make it a good design. I seriously doubt it would be acceptable to any of the major home building code organizations.

 

[Rabbit]

With your experience what do you think about the way Grand Design mixes the soft hose and PEX in the construction of their trailers. If you have not had any problems with the plumbing in your trailer then that is great. What ever you do don’t touch the connections behind the Nautilus panel. I replaced my water pump the other day and in the process caused one of the connections behind the Nautilus to leak. By the time I got that connection fixed a three way tee was leaking. By the time I got the leaks fixed I had spent all afternoon. The braided soft hose GD uses is slightly larger OD than PEX and needs to be heated to get PEX clamps on and the ID is much larger than the PEX connectors that GD uses which causes the leaks.

What are your recommendations for fixing the soft hose leaks that result from GD using PEX connectors that are much smaller then the soft hose ID?

See response below.

 

[Always Learning]

See response below.

Sorry I don’t see any additional information.

 

[Rabbit]

Mine is all braided tubing as far as I can tell. I'm thinking of replacing it so everything is PEX. GD says braided tubing is the "industry standard" but that does not make it a good design. I seriously doubt it would be acceptable to any of the major home building code organizations.

Unfortunately it is acceptable per CSA for the RV industry, which the US accepts, but braided hose/tubing is not per standard in US building codes as supply line. Personally and from experience in the waterworks industry, I don’t like it. PEX clamps were make to use on extruded PEX pipe, which I believe is ID controlled. Perhaps the clamps used on RVs is special somehow. I don’t know. The RV industry uses it for obvious reasons and if the clamp is installed correctly and the stars are aligned, that use is I guess okay. But! If not clamped sufficiently or the fitting or tubing is not on tolerance, maybe not. The company I worked for made slip on self clamping o-ring sealed plumbing fittings that were not guaranteed to work on anything other than pipe and tubing with a smooth OD within certain tolerances. That’s not braided hose. And I agree, if it doesnt leak don’t mess with it.

 

[Always Learning]

And I agree, if it doesnt leak don’t mess with it.

Unfortunately as the system ages they do leak. When I say touch the connection all it takes is a little pressure or a slight pull on the line and a leak is created. I would think the RV industry is large enough to have custom hoses and/or connectors made that work for both PEX and soft hose if they want to put both in the trailer.

The soft hose connection leaks are why there are threads on this forum about owners replacing all soft hose with PEX. Why is it the customer/end users responsibility to repair badly designed and implemented systems in these trailers. This forum is great because other owners posted about the leaks and I added PEX tools, connectors, clamps and spare PEX pipe to my repair kit. We are full time and always in the middle of no-where so I have to be prepared to fix any problem I can. I have had previous trailers with all PEX lines and never had any leaks. (End of rant)

 

[Rabbit]

Unfortunately as the system ages they do leak. When I say touch the connection all it takes is a little pressure or a slight pull on the line and a leak is created. I would think the RV industry is large enough to have custom hoses and/or connectors made that work for both PEX and soft hose if they want to put both in the trailer.

The soft hose connection leaks are why there are threads on this forum about owners replacing all soft hose with PEX. Why is it the customer/end users responsibility to repair badly designed and implemented systems in these trailers. This forum is great because other owners posted about the leaks and I added PEX tools, connectors, clamps and spare PEX pipe to my repair kit. We are full time and always in the middle of no-where so I have to be prepared to fix any problem I can. I have had previous trailers with all PEX lines and never had any leaks. (End of rant)

I did also, knowing the likelihood of leaks down the road. I added a worm hose clamp to the braided tubing when upgraded the toilet to a Dometic 310.

 

[Brother_Bluto]

It is the PEX fittings used for reinforced vinyl that will eventually leak... especially in cold weather. I have yet to find a manufacturer of PEX crimp fittings (i.e. barbed) that will certify they are compatible with reinforced/braided vinyl. The ID of reinforced vinyl is slightly larger, and requires more defined barbed fittings made for vinyl (with a screw clamp). I have also yet to find a true vinyl barb to PEX crimp transition fitting which leaves using a threaded vinyl barb jointed to a threaded PEX crimp fitting for a proper transition... or just get rid of the reinforced vinyl altogether.

FWIW - there isn't a "soft" and "hard" PEX. There are two main potable-water types of PEX - PEX-A and PEX-B. Both are sold in coils or as sticks and no difference between one version in a stick or that same version in a coil. PEX-A is easier to work with IMO as it a bit more flexible, less prone to leak from a kink and has less memory. Both PEX-A & B can use the PEX brass or plastic crimp fittings & push to fit fittings... but only PEX-A can be used with Uponor-style expansion fittings.

 

[Scott'n'Wendy]

Fittings that rely on an o-ring to seal, such as SharkBite brand and similar, are not certified for use on braided tubing. Barbed fittings with pipe clamps (worm gear, even PEX clamps) are about the only reliable connection. O-ring fitting MIGHT be made to seal, but the seal will not be reliable for the long term, especially with vibration.

The worm gear clamp on factory RV braided hose is at best a temporary measure-they will also leak. They are mated to pex fittings. The only reliable connection would be to change the fitting or the hose and then use the correct clamp...depending on which route you took.

I agree with what you say. If you are doing more than changing "like for like", make sure you know what you are doing or call a licensed tradesman.

PS..I have grown to hate the title "Tech". It's thrown around like a catch-all for anybody servicing any machine/appliance/vehicle/trailer/blender. Proven training? You may have lots...or a little. I have a friend who told me a few years ago. "Hey! they call me a tech now. Don't know what's different between yesterday and today though. lol"

 

[Scott'n'Wendy]

Unfortunately it is acceptable per CSA for the RV industry, which the US accepts, but braided hose/tubing is not per standard in US

The braided soft hose has an ASTM rating, American Society for Testing and Materials.

Just FYI, but there is some suggestion out there that GD is using a different soft hose in newer units that has an ID closer to pex so leaks are less frequent. Still using pex clamps on soft hose which is a problem, but hey...its a bit better!

 

[Rabbit]

True PEX tubing/pipe is dimensionally CTS (copper tube size) which is the size of virtually all water service line pipes and fittings approved for water distribution and plumbing systems as set by AWWA standards (American Water Works Assn), this includes Sharkbite brand. Braided pipe has an ASTM standard, but that’s not a guarantee it’s compatible with or equal to CTS specs. That’s where the compatibility problem stems. ASTM only means “all” tubing made to that spec will be similar in dimension, material and other characteristics, but doesn’t mean it will be compatible with CTS fittings.

The braided tubing in my GD 3100RD is marked CSA, a Canadian Standard which makes the tubing permissible for use in RV plumbing. But it could never be used in building construction, for instance. Virtually all plumbing fittings intended for building construction are made to AWWA standards, not CSA, although some ASTM specs are compatible with AWWA.

The disconnect is PEX and braided tubing are not the same animal.

Barbed fittings are not AWWA. PEX are. I have no idea how or why braided tubing became acceptable in RVs, so I’ll stop without suggesting it’s not acceptable. According to CSA it is. But I stand by my original advice that Sharkbites and similar o-ring sealed fittings are not reliable on braided tubing. Use barbed fittings with a suitable pipe clamp.

 

[TravelHabit]

The thing that bothers me is that I can't believe the cost savings of braided tubing is really that much compared to PEX for the lengths we have in a RV. Particularly when one compares this to the purchase price.

I made my dissatisfaction clear in the recent survey I received as a result of my last GD purchase (2022 22RBE). In the survey response I marked down trailer quality and noted in the comments this was entirely due to use of braided tubing and not PEX (happy in all other respects). The irony is that I also responded quality was the #1 priority in my selection process. At the time I purchased I didn't know enough to look for PEX. I also put in the comments that I would have been willing to pay a little more for PEX. Given GD can stand behind the CSA approval, I doubt that will change the reality though

Again, I maintain that even though it is an industry standard that doesn't make it a good design choice ... as others have confirmed.

 

[huntindog]

The thing that bothers me is that I can't believe the cost savings of braided tubing is really that much compared to PEX for the lengths we have in a RV. Particularly when one compares this to the purchase price.

I made my dissatisfaction clear in the recent survey I received as a result of my last GD purchase (2022 22RBE). In the survey response I marked down trailer quality and noted in the comments this was entirely due to use of braided tubing and not PEX (happy in all other respects). The irony is that I also responded quality was the #1 priority in my selection process. At the time I purchased I didn't know enough to look for PEX. I also put in the comments that I would have been willing to pay a little more for PEX. Given GD can stand behind the CSA approval, I doubt that will change the reality though

Again, I maintain that even though it is an industry standard that doesn't make it a good design choice ... as others have confirmed.

I think the cost savings is in labor. Having flexible hose to the termination points speeds up production a lot. 100% pex plumbing means pretty precise measuring and cutting/clamping as there is limited amount of flex to be had.

 

[TravelHabit]

Perhaps, but even then it can't be that much. I noted the GD assembly techniques for braided tube appear to use PEX crimpers and similar tools (which is the primary source of the problem in first place!!). That is, the labor time for connections is probably the same for braided or PEX. Moreover, for each model, the lengths could be determined once and and all future installs would be identical (or close enough). Plumbing wise, it would actually be much easier than typical home construction where each PEX run is more or less custom. Agreed, there is less flex but can that really drive labor cost for an assembly line?

On the other hand, there clearly is a cost savings that GD sees. Its certainly combination of engineering design, material, and labor. I recall when I was working as an engineer and our NASA customer asked for a proposal for a seeming minor change... they were shocked by the amount we proposed. In that case the price was almost completely due to the NRE associated with drawing changes that rippled through the design causing significant hours of engineering time for those updates. The part cost and manufacturing time was essentially the same. That said though, from what I understand GD does not require the same detailed drawings since much is left to the individual builders due to semi-custom manufacturing methods.

 

[huntindog]

Perhaps, but even then it can't be that much. I noted the GD assembly techniques for braided tube appear to use PEX crimpers and similar tools (which is the primary source of the problem in first place!!). That is, the labor time for connections is probably the same for braided or PEX. Moreover, for each model, the lengths could be determined once and and all future installs would be identical (or close enough). Plumbing wise, it would actually be much easier than typical home construction where each PEX run is more or less custom. Agreed, there is less flex but can that really drive labor cost for an assembly line?

On the other hand, there clearly is a cost savings that GD sees. Its certainly combination of engineering design, material, and labor. I recall when I was working as an engineer and our NASA customer asked for a proposal for a seeming minor change... they were shocked by the amount we proposed. In that case the price was almost completely due to the NRE associated with drawing changes that rippled through the design causing significant hours of engineering time for those updates. The part cost and manufacturing time was essentially the same. That said though, from what I understand GD does not require the same detailed drawings since much is left to the individual builders due to semi-custom manufacturing methods.

I got to tour the Sabre factory when I bought one of their models. It did not run like a automobile factory with a seperate line for each model. They had one line that produced all of their models. They did try to bunch like models together , but it wasn't always possible. So things like pex were just taken from bulk spools as needed.
They simply did not produce enough units to justify each model having it's own line. I am betting that GD operates pretty much the same.... This also explains a lot of the haphazard construction we see.

 

[Steven@147]

I think the cost savings is in labor. Having flexible hose to the termination points speeds up production a lot. 100% pex plumbing means pretty precise measuring and cutting/clamping as there is limited amount of flex to be had.

A lot to this, and more use of 90* elbows and clamps since pex doesn't bend too well. Like as said more precise measuring of pex tubing lengths and more thought put into installation. I don't think it would take that much more time for labor to use all pex using experienced pex plumbing installers and seeing as how GD has pretty much separate manufacturing lines like for Momentum / Solitude, Reflections, Imagine / Transend etc. but the factory may think it does. But then again like I said "experienced pex plumbing installers" , not something I think RV manufacturing lines care much about, and quality work, just good enough is ok with them, that's the sad part..

Right now I'm fixing another flex to pex leak, from T's behind the basement wall, over and up into the bathroom and connection to the dual sinks and faucets. And if am going to get in there I'll do both cold and hot lines.

 

[huntindog]

A lot to this, and more use of 90* elbows and clamps since pex doesn't bend too well. Like as said more precise measuring of pex tubing lengths and more thought put into installation. I don't think it would take that much more time for labor to use all pex using experienced pex plumbing installers and seeing as how GD has pretty much separate manufacturing lines like for Momentum / Solitude, Reflections, Imagine / Transend etc. but the factory may think it does. But then again like I said "experienced pex plumbing installers" , not something I think RV manufacturing lines care much about, and quality work, just good enough is ok with them, that's the sad part..

Right now I'm fixing another flex to pex leak, from T's behind the basement wall, over and up into the bathroom and connection to the dual sinks and faucets. And if am going to get in there I'll do both cold and hot lines.

I am aware that GD has seperate lines for Momentums, Solitudes etc. But how many different models share those lines? The RV industry does not use any robots or have a system where the right part arrives at the right time to be installed like the automotive industry does. It would be far to expensive at the volumes they produce.

 

[Palmetto]

Just got back from a week long spring break trip with my family. Second morning of the trip we had water coming out from under my shower. (2021 Transcend Xplor) Got the rig home, and put it in my shop. After pulling the shower out, I found plastic pex fittings with vinyl hose. I made the decision to repipe the whole trailer with PEX. Piss on that vinyl crap. I also had to remove almost all of my insulation under the trailer. We are in a warm climate, so Im not too worried about the insulation. I dont plan on putting it back.

anyway, I started the repipe yesterday, and have a pretty good handle on it in just a few hours. It goes pretty fast. One thing is for sure, when I am done I will have closed up most of the rodent entry points! I did not realize the left so many openings for the little buggers!